Muffler with frusto-conical baffle members spaced along central tube



Nov. 28, 1967 I w oss ETAL 3,354,986

MUFFLER WITH FRUSTO-CONICAL BAFFLE MEMBERS SPACED ALONG CENTRAL TUBEFiled July 21, 1965 IIII n o 11 f; 9 2 E n LL 0 O O o ,\m o

0 I M r 2 l o o 3 Z 0 II (I?! v 9' LL. C) Q E INVENTORS WILLIAM A MOSS AROSE E. GRIFFIN ATTO RN EYS Patented Nov. 28, 1967 3,354,986 MUFFLERWITH FRUSTO-CONICAL RAFFLE MEMBERS SPACED ALONG CENTRAL TUBE William A.Moss and Rose E. Grifiin, Lafayette, La., assignors, by direct and mesneassignments, of fifty percent to said Moss, twenty-five percent to JamesD. Parkerson, and twenty-five percent to J. Arthur Roy, all ofLafayette, La.

Filed July 21, 1965, Ser. No. 473,631 9 Claims. (Cl. 18157) The presentinvention relates to mufiiers for internal combustion engines and moreparticularly to a novel and improved muffler structure which is highlyeffective in reducing unwanted noise generated by exhaust gasses from aninternal combustion engine while creating only a small amount of backpressure thereby enabling efiicient, economical operation of an internalcombustion engine.

Various muffler designs are well known in the internal combustion engineart. These mufflers are normally constructed to minimize back pressureand noise due to expanding gasses. Many of these mufflers employ dividedflow passageways for exhaust gasses but all have met with certainproblems. In some cases back pressure produced by such mufflers isunnecessarily high and/ or noise reduction is not maximized.

It is an important object of the present invention to provide a new andimproved mufiier construction which enables quiet, economical operationof an internal combustion engine. Another important object of thisinvention is to provide a muffler in accordance with the precedingobject which can easily be taken apart for cleaning when desired andreassembled with ease.

Still another object of this invention is to provide a muffler inaccordance with the preceding objects which is highly compact withminimized cross sectional area facilitating its compact mounting on anautomobile or other apparatus with which it is used.

According to the invention, the mufiler comprises an elongatedtubular,.imperforate casing defining an outlet opening and an inletopening aligned therewith. A tu-be extends substantially axially of thecasing and has a closed end spaced within and apart from the outletopening. A plurality of frusto-conical members surround the tube andextend between the tube and the casing to define at least twooverlapping-gas expansion chambers. At least two of the plurality offrusto-conical members are spaced apart intermediate the outlet andinlet openings to define a flow chamber of larger volume than either ofthe expansion chambers and arranged in axial alignment with theexpansion chambers. Apertures are provided in the frustoconical membersand in the centrally located tube to provide a gas flow passageway froma portion of the tube adjacent the inlet opening through the expansionchambers and the flow chamber to the outlet opening.

In the preferred embodiment, two overlapped frustoconical members areprovided at one end of the ca ing and two frusto-conical members areprovided at the other end with a space extending between the pairs offrustoconical members. This space acts as a flow chamber to decreasemuifier back pressure and thereby permit economical operation of theinternal combustion engine with which the muffler is used.

These and other objects, features and advantages of the invention willbecome apparent from the following specification and attached drawingsin which:

FIG. 1 is a cross sectional view taken on a vertical plane through thecenter of a preferred embodiment of the muffler of this invention;

FIG. 2 is a side view of an element thereof; FIG. 3 is a side view ofanother element thereof; and FIG. 4 is a rear view of a frusto-conicalelement as shown in FIG. 2 with the element of FIG. 3 positionedtherein.

With reference now to the drawings a preferred embodiment of the mufflerof this invention is illustrated at 10 and comprises an imper'foratecasing 11 containing an inner axially aligned tube 12 having surroundingfrustoc nical members 13, 14, 15 and 16 extending from the tube 12 tothe inner surface of the casing 11. The frustoconical members arearranged to extend axially of the casing as best shown in FIG. 1dividing the casing into expansion chambers 17 and 18 spaced from aforward expansion chamber 19 with a flow chamber 20 intermediatethereof.

The imperforate casing 11 is preferably a cylindrical pipe composed of ahigh temperature resistant material such as solid copper pipe type K.Means such as threads 22 and 23 are carried at inlet and outlet ends ofthe casing respectively. Since the casing 11 is circular in crosssection, and all flow through the elongated mufiler is substantiallyfrom end to end thereof, a minimum cross sectional area for the outerconfiguration of the muffier may be maintained. Suitable adapters (notshown) are provided for the ends of the rnufiier to attach an exhaustpipe from the manifold on a threaded flange with the exhaust pipeabutting the rear end of the central tube 1.2 and with a tail pipeattached to the outlet end 23 through a suitable reducing flange.

In the specific example of this invention, casing pipe 11 preferably hasan inside diameter of 2% inches with an outside diameter of 2 /8 inchesbeing a solid copper seamless pipe having a length of approximately 21inches.

The inner tube 12 is preferably a solid copper pipe which extendsaxially of and within the outer casing having a closed forward endpinched together at 24 as best seen in FIG. 3. The pinched together end24 is provided with crossed plates 25 and 26 which act to center thepipe within outer tube 11 as will be described. Plates 25 and 26 arewelded or otherwise fixed to the pinched end 24, The copper pipe 12 ofthe preferred embodiment has an outside diameter of inch and a series ofperforations extending from /2 inch of its end adjacent the intake endof the casing in a first and second group towards the closed end.Perforations 27 lie within the frusto-conical member 14 and preferablycomprise four rows of five circular openings with the rows spacedapproximately about the circumference of the pipe. The group ofperforations 28 preferably comprises four rows of seven openings alignedwith the rows of group 27 with all of the openings preferably having adiameter of Ms inch. The particular material of the tube 12 as well asits dimensions may vary considerably depending upon the particular sizeengine with which the mufiler is used as may the dimensions of otherelements of the mufflers while their relative dimensions to each otherare preferably substantially as described. The spacing, number, size andlocation of the holes 27 and 23 within baffies 13 and 14 is importantfor optimum operation of the invention.

The frusto-conical members 13, 14, 15 and 16 act as battles to provideexpansion chambers and a flow chamber within the mufiler. Each of thebaffies preferably has a large or base end outside diameterapproximately inch greater that the inner diameter of the casing 11 anda small end inner diameter approximately 4 inch less than the outsidediameter of pipe 12. The baflle members may be made of any heatresistant material such as 16 ounce copper and can be formed with awelded or soldered seam. Each bafile preferably has a length ofapproximately 4 inches in the preferred embodiment with the extreme endbaffle nearest the intake end having a length approximately 10% longer.Each of the baflle members with the exception of the two central membersare over- 3 lapped or inserted into one another for a distance ofapproximately 1 inch.

The baflles contain a series of perforations which are preferablyelongated slots extending in thirteen rows equally spaced about thecircumference thereof with approximately 5 slots of .07 square inch areain each baffle row. In some embodiments, the smaller diameter opening ofthe baflle members are soldered or welded to the tube 12. The forwardbaffle member 16 is provided with a closed end cap formed by end 24 andthe plates 25 and 26 may be welded or tightly fit within the inside ofouter tube 11 as best shown in FIGS. 1 and 4 to centrally locate boththe baffle and the pipe within the tubular casing. Preferably theperforations extend within the baffles approximately inch from thecasing 11 and approximately /8 inch from the tube 12. While thesedimensions are not absolute as previously described, they give bestresults in the preferred embodiment of the invention.

The baffle members 13, 14, 15 and 16 are preferably force fit over pipe12. In all cases the metallic baffle members are welded or braised topipe 12. The assembled baffle members and pipe are then positioned inthe casing 11 where they are held in place by a force fit since thediameters of the baffle members and plates 25 and 26 are slightlygreater than the casing 11. Thus the baffle n1embers are preferablyformed of a relatively thin resilient metal such as copper or a copperalloy. Due to the force fit assembly the mufiier can be easily takenapart for cleaning when desired and later reassembled.

The spacing between baffle 14 and 15 is critical and provides for anenlarged flow passageway which is believed to create a partial vacuumduring operation of the device to enhance flow of gasses from theexpansion chambers 17 and 18 through the muffler. It is important thatthis chamber be formed with a spacing between facing ends of adjacentbaffles greater than one half the axial length of the shortest baffleemployed. The flow passageway includes the space between the outersurface of the concentric tube 12 and the inner surface of the outerwall of casing 11. In the preferred embodiment the axial distance thatthe flow chamber 20 extends between ends of its adjacent bafile membersis 3% inch. Preferably the ratio between the axial uninterrupted lengthof the flow chamber 20 between its adjacent bafiies, to the distancerepresented by the length of an adjacent baffie plus the length of theflow chamber is approximately 3% to 7%,.

In operation of the muffler of this invention, gasses from the manifoldof an internal combustion engine are passed into the inner tube 12 inthe direction of the arrows shown. Some of these gasses will goimmediately into the expansion chambers while the greater percentage ofthe gasses will flow towards the forward end to create a zone ofchurning gasses within the pipe in the forward batfle member 16. Thischurning action causes more of the gasses from the engine to flowthrough openings 27 and 28 directly into the expansion chambers 17 and18. The baffies inhibit the sudden discharge of expanding gasses bymeans of redirecting, reflecting and controlling the passage of gassesthrough the muffler. From the expansion chambers 17 and 18 a slightvacuum created in flow chamber 20 will draw the gasses therethrough andallow them to pass onwardly into expansion chamber 19 and out of themuffler through exhaust end 23 to the tailpipe when used. Thus gassespass through holes 27 and 28, baffles 13, 14, chamber 20, baflle 15 andout through baffle 16. This flow pattern is significant in providing forreduced back pressure within the mufller while allowing rapid expansionand expulsion of gasses. In addition, the multiple chambers provided actto acoustically trap vibrations caused by pulsing of the motor and alsoact as vibration absorbers to smooth the pulsing out into a smooth pulsepattern thereby deadening the noises created by explosion of the gasseswithin the motor.

While a specific embodiment .of this invention has been shown anddescribed, it should be understood that many variations thereof arepossible. For example, the specific number of battle members can bevaried so long as at least one enlarged flow chamber is providedinterspaced 5 between baffle members. In some cases where extremelylarge volumes of exhaust gasses must be muffled and dispersed, two ormore flow chambers can be made in a mufiier construction in accordancewith the present invention. Similarly larger numbers of expansionchambers can be formed by the use of additional baflle members. Sizesand dimensions may vary preferably consistent with the proportions ofthe values given.

In view of the many variations possible, this invention is to be limitedonly by the spirit and scope of the appended claims.

What is claimed is:

1. A compact muffler comprising an elongated tubular, imperforate,casing defining an inlet opening and an outlet opening alignedtherewith,

a tube extending substantially axially of said casing and having aclosed end spaced Within and apart from said outlet opening,

a plurality of frusto-conical members surrounding said tube and definingat least two overlapping expansion chambers and acting as baffle means,

at least two of said plurality of members being spaced apartintermediate said outlet and inlet openings to define a flow chamber oflarger volume than either of said expansion chambers and arranged inaxial alignment therewith,

and apertures defined by said members and said tube to provide a gasflow passageway from a portion of said tube adjacent said inlet openingthrough said expansion chambers and said flow chamber to said outletopening.

2. A compact muffler in accordance with claim 1 wherein two pairs offrusto-conical members are provided,

said apertures defined by said tube being positioned within one of saidpairs of frusto-conical members spaced substantially adjacent said inletopening.

3. A compact mufiler in accordance with claim 1 wherein saidfrusto-conical members are force fit within said casing whereby saidmuffler may be easily disassembled for cleaning.

4. A compact muffler in accordance with claim 2 wherein said aperturescomprise two groupings of openings with one group in each of thefrusto-conical members of said pair spaced substantially adjacent saidinlet opening.

5. A compact mutfier comprising an elongated circular, imperforatecasing defining an inlet opening and an aligned outlet Opening,

a tube extending substantially concentrically within said casing andhaving a first closed end substantially adjacent said outlet opening anda second opened end substantially adjacent said inlet opening,

a plurality of frusto-conical members surrounding said tube and definingat least two overlapping expansion chambers and acting as baffle meanswith apertures provided in said members interconnecting said 60chambers,

at least two of said plurality of members being spaced apartintermediate said outlet and inlet openings to define a flow chamberextending axially of said casing between said tube and said casing,

and apertures defined by said members and said tube to provide a gasflow passageway from a portion of said tube adjacent said inlet openingthrough said expansion chambers and said flow chamber to said outletopening.

6. A compact mufl ler in accordance with claim 5 wherein fourfrusto-conical members are provided with two of said frusto-conicalmembers being spaced apart from two others of said frusto-conicalmembers to define said flow chamber whereby exhaust gasses entering saidtube at said inlet opening flow through said two baffle memberspositioned substantially adjacent said inlet opening to said flowchamber and subsequently through said two members positioned adjacentsaid outlet opening whereby said members act as bafiies to inhibit thesudden discharge of expanding exhaust gasses by redirecting, reflectingand controlling the passage of said gasses through said mufiler. 7. Amuflier in accordance with claim 6 wherein said closed end of said tubeis pinched together and carries a plurality of plate means forpositioning said tube centrally of said casing.

8. A mufiier in accordance with claim 6 wherein said tube aperturescomprise a first and second group,

said first group of apertures being surrounded by one battle andcomprising four circumferentially arranged axially extending rows witheach row containing seven openings. 9. A muffler for use in conjunctionwith an engine which normally produces exhaust gasses,

said mufiler comprising an elongated casing defining an inlet openingand an outlet opening aligned therewith, a tube extending substantiallyaxially of said casing and having a closed end spaced within and apartfrom said outlet opening and an opened end positioned within said casingspaced from said inlet opening, a plurality of frusto-conical bafiiemembers extending from said tube to said casing with said bafile membersdefining a plurality of apertures to provide an axially extendingpassageway through said muffler,

at least two of said plurality of members being spaced apartintermediate said outlet and inlet openings to define a flow chamberwith others of said bafile members overlapping each other to provideexpansion chambers,

said tube defining two groups of apertures each lying in separate bafilemembers near said inlet opening to provide for passage of exhaust gassesfrom said groups through said expansion chambers and said flow chamberto said outlet opening.

References Cited FOREIGN PATENTS 3/ 1921 Great Britain. 2/1925 GreatBritain.

ROBERT S. WARD, JR., Primary Examiner.

1. A COMPACT MUFFLER COMPRISING AN ELONGATED TUBULAR, IMPERFORATE,CASING DEFINING AN INLET OPENING AND AN OUTLET OPENING ALIGNEDTHEREWITH, A TUBE EXTENDING SUBSTANTIALLY AXIALLY OF SAID CASING ANDHAVING A CLOSED END SPACED WITHIN AND APART FROM SAID OUTLET OPENING, APLURALITY OF FRUSTO-CONICAL MEMBERS SURROUNDING SAID TUBE AND DEFININGAT LEAST TWO OVERLAPPING EXPANSION CHAMBERS AND ACTING AS BAFFLE MEANS,AT LEAST TWO OF SAID PLURALITY OF MEMBERS BEING SPACED APARTINTERMEDIATE SAID OUTLET AND INLET OPENINGS TO DEFINE A FLOW CHAMBER OFLARGER VOLUME THAN EITHER OF SAID EXPANSION CHAMBERS AND ARRANGED INAXIAL ALIGNMENT THEREWITH, AND APERTURES DEFINED BY SAID MEMBERS ANDSAID TUBE TO PROVIDE A GAS FLOW PASSAGEWAY FROM A PORTION OF SAID TUBEADJACENT SAID INLET OPENING THROUGH SAID EXPANSION CHAMBERS AND SAIDFLOW CHAMBER TO SAID OUTLET OPENING.